Constructing Bluebird Boxes

Constructing the Perfect Home for Bluebirds

Download bluebird nesting box plans (requires Adobe Acrobat).

One of the easiest ways to assist bluebirds in your area is through the placement of nesting boxes.  Bluebirds are not very finicky - they will nest in a wide variety of nesting boxes.  The traditional 1 ½-inch entrance hole and sloping roof box is more widely used; however, studies have indicated that bluebirds often prefer the slot nesting box over traditionally-styled nesting structures.  If you have had little success attracting bluebirds with traditional boxes, the slot box may work best for bluebirds in your area.

Construct boxes using untreated wood.  Ideally, boards used in nest box construction should be ¾ inch thick.  If smooth lumber is used in nest box construction, roughen the wood on the interior of the box just below the entrance hole.  This makes it easier for young birds to climb out of the nesting box when ready to fledge.  Assemble boxes using screws, aluminum nails or galvanized nails.

Entrance holes should be cut precisely 1 ½ inch in diameter.  Larger holes permit European starlings to enter the box.  These birds are exotic to the United States and will displace most cavity nesting birds during nesting season.

If you have a problem with flying squirrels increasing the size of the entrance holes to your boxes, install metal entrance hole shields around the 1 ½ inch hole.  These shields can be obtained from stores specializing in bird-related items.

All boxes should be provided with drainage and vent spaces.  Drainage holes can be created by cutting ¼ inch off each of the four corners of the bottom of the box, or by drilling four to five ¼-inch holes in the bottom panel.  Drill holes at the top of the side panels or leave spaces between the top of the box and the sides to provide ventilation.

The outside of bluebird boxes should be painted a light color.  Boxes painted light colors stay cooler than those painted dark colors.

Do not equip a bluebird nesting box with a perch.  Bluebirds do not need perches; however, nest competitors such as house wrens and house sparrows will use perches to gain access to a box.

Measuring from the ground to the bottom of the box, mount your bluebird box at least four feet, but no more than 15 feet above the ground.  Whenever possible, mount bluebird nesting boxes on poles made of metal or sunlight-resistant PVC pipes.  Boxes placed on such structures are easier to protect from rat snakes, raccoons and other nest predators.  A piece of ¾ inch electrical conduit makes an ideal nesting pole.

Boxes should be equipped with predator guards.  One of the simplest ways to prevent predators from entering boxes is to smear automotive grease on the pole beneath the boxes.  An alternative method is to place a sheet metal cone (36 inches in diameter) around the pole beneath the box.

If you must mount boxes on trees, leave at least a one-inch space between the nail or lag bolt and the box.  This will allow the tree on which the box is mounted to grow without forcing the box off its trunk.

Boxes should be placed in open habitats with sparse trees and low vegetation.  Many bluebirds' nest box efforts fail because boxes are erected directly in shrubby and forest conditions.

Position boxes so that they face a tree or shrub located within 25 to 100 feet of the box.  These woody plants provide safe landing areas for fledglings on their first flight.  A young bluebird landing on the ground is vulnerable to cats, dogs and other predators.  Bluebirds do not seem to prefer boxes facing in a particular direction.

Boxes should be erected 100 yards or more apart. Nesting bluebirds will often fight with one another when boxes are placed close together. Another option is to mount pairs of boxes about 25 meters apart with each pair 100 yards from the next. This allows another species such as the Carolina Wren, Chickadee, Tree Swallow or Tufted Titmouse to use one while the Bluebirds use the other.

Monitor boxes once a week during the nesting season.  Once hatchlings appear, do not check boxes after the young are 12-14 days old as the young might try to leave their nesting box before they are ready to fly.

It is important to clean out the nest boxes entirely at the end of each breeding season, or before the next nesting season if you want to have return visitors.

Remove sparrow nests as soon as they are discovered.  While this procedure may have to be repeated several times, eventually the sparrows will nest elsewhere.

Do not take nesting boxes down in the winter season.  Boxes make ideal roosting sites for bluebirds on cold winter nights.

Additional Resources:

Bluebird Box Monitoring Program

For more information on bluebirds in Georgia, contact WRD's Nongame Conservation Section, (478) 994-1438.




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